Refrigerating apparatus



June 10, 1941.

C. M. SANDERS, JR REFRiGERATING APPARATUS Filed Sept. 3, 1938 WITNESSES:

dIHLg. v

INVENTOR V ATTORNE operation.

apparatus incorporating my Patented June 10, 1941 UNITED STATES PATENT OFFICE memififinmws Charles M. Sanders, Jr., Oak Park, 11]., asslgnor to Westinghouse Electric a Manufacturing Company, East Plttsburgh, Pa., a corporation of v Pennsylvania ApplicationSeptember a, 1938, Serial no. 228,299

11 Claims. (Cl. 62-4) My invention relates to refrigerating apparatus, more particularly to refrigerating apparatus including a plurality of evaporators and a variable capacity compressor, and it has for an object to provide improved apparatus.

An object i to provide improved means for varying the compressor capacity in accordance with the capacity of the evaporators that are in In accordance with my invention,-I associate with each evaporator a definite cylinder or group of cylinders of-"suiliclent capacity to serve the evaporator, and I provide a control whereby the associated cylinder 01' cylinders are loaded when the evaporator is rendered effective and unloaded when the evaporator is rendered ineffective. Thus, the compressor capacity at all times substantially equals the evaporator capacity that is rendered efiective, so that the suction pressure is maintained at a suitable value. A control is provided for at least one and preferably each evaporator whereby the same may be rendered eflective or ineffective. Such control may comprise a thermostat or other instrument for automatically controlling the evaporator in accordance with the cooling demand on the evaporator. Provision is also made for operating the compressor when any evaporator is rendered effective and for shutting down the same when all the evaporators are rendered ineffective. v

Fig. l is a diagrammaticview of refrigerating invention; and Fig. 2 is a detail sectional view showing the unloader.

I2, comprising evaporators 12a and I21), and

an evaporator l3. The evaporators I20 and l2b serve a common cooling demand, are simultaneously controlled, and may be considered so far as the present invention is concerned, as one evaporator. The evaporators ll, l2 and It may serve independent cooling demands, or they may be arranged in any other desired manner. It is to be understoodthat the evaporators are illustrated atically on the drawing. They may be enclosed in suitable casings and provided with forced is well understood in the art and the illustration of which has been omitted in order to simplify the drawing and make the invention more apparent. The motor compressor unit ll includes a compressor having ei t cylinders and a motor II for driving the same. Each cylinder is provided air circulation, all ofwhich 1 nec with any suitable form of unloader mechanism whereby the cylinder may be unloaded. One form of such mechanism is illustrated in Fig. 2. in which th suction valves II are held open for unloading the cylinder. The unloader mechanism includes a movable member l8 having flngers l8 adapted to engage the valves ll, a spring 2| adapted to bias the member l8 downwardly with sufficient force to hold the valves in open position for unloading, and a solenoid 20 adapted, when energized, to raise the movable member l8 and permit the valve H to close for loadin the cylinder. It is to be understood that any other suitable unloader mechanism may be substituted without departing from the invention.

A suction conduit 22 connects the several evaporators to the motor compressor unit, and is preferably arranged to convey the vaporized refrigerant through th motor-containing portion of the casing.

, The refrigerant compressed by the compressor is conveyed through conduits 23 to a combined condenser and receiver 24. From the latter, the condensed refrigerant is conveyed through a liquid line 25 and branch conduits 26 to the several evaporators.

The flow of liquid refrigerant to each evaporator is preferably controlled by a shut-off valve 21 in the branch conduit 26. Each evaporator is provided with suitable means for controlling the associated valve 21 in response to the cooling demand of the evaporator. Inasmuch as the evaporators ll, l2 and ll of the present embodiment serve independent cooling demands, they are provided with thermostats T1, T2 andTs. respectively, each thermostat being responsive to the temperature maintained at a low value by the evaporator. As will be apparent, each thermostat may be disposed in the enclosure cooled by the evaporator. Each thermostat controls its .valve 21 through a solenoid 2i,-the latter being arranged to open the valve when it is energized and to close the valve when it is deenergized.

In the illustrated embodiment, the first two cylinders are associated withthe evaporator II, the next four cylinders are associated with the evaporator l2, the latter comprising twice as much surface as either of the otherevaporators, and the, last two cylinders are associated with the evaporator l3. Accordingly, the unloader solenoids 2. of the first two cylinders are conin parallel with the solenoid 28 of the first evaporator. as will berfully apparent from the drawing. Similarly. the remaining unloader solenoids 28 are connected in parallel with the solenoids 28 of the associated evaporators.

The motor I6 is supplied with electric current from line conductors L1, L and La, the supply being controlled by a starter coil or relay 29. Each of the solenoids 28 is adapted, when energized, to close a pair of contacts 3|. The several contacts 3| are connected in parallel between the line conductor L1 and the coil 29 so that energization of any one of the coils 28 energizes the coil 28 and closes the circuit to the compressor motor.

, Operation Assuming the temperature of the space or enclosure served by the evaporator l I to increase above the value desired to be maintained therein, the thermostat T1 closes its contacts, thereby energizing the solenoid 28 and the unloader solenoids associated therewith. The solenoid 28 opens the valve 21 to supply liquid refrigerant to the evaporator II and the unloader mechanisms operate to load the first two cylinders, thereby providing the amount of compressor T3 is adapted to effect admission of refrigerant to the evaporator l3 and'to load the last two cylinders to serve the evaporator l8. a

Each of the thermostats is adapted to open its contacts in response to a temperature supply below that at which it closes its contacts. The as- What I claim is:

1. A refrigerating system comprising a plurality of evaporators, a compressor comprising a plurality of compressor elements, a motor for driving said compressor, means associated with one evaporator for initiating and terminating flow of refrigerant thereto automatically in response to a load condition thereof and simultaneously therewith loading and unloading, respectively, one of said compressor elements.

2. A refrigerating system comprising a plurality of evaporators, a compressor comprising a plurality of compressor elements, a motor for driving said compressor, means associated with one evaporator for selectively rendering the same eflective or ineifective, and means controlled by the lastmentioned means for loading and unloading one of said compressor elements when said one evaporator is rendered effective and ineifective, re-

spectively.

3. In refrigerating apparatus, the combination of a plurality of evaporators, a compressor having a compressor element or elements associated with each evaporator, a motor for driving said compressor, and means associated with each evaporator for initiating and terminating flow of refrigerant thereto and for simultaneously loading and unloading, respectively, the associated compressor element or elements.

4. Apparatus as set forth in claim 3, and further including means for automatically energizing said. motor whenever any evaporator is rendered effective and for deenergizing saidmotor when all evaporators are rendered ineifective.

5. In refrigerating apparatus, the combination of a plurality of evaporators, a compressor having a compressor element or elements associated sociated solenoid 28 is thereby deenergized and closes the valve 21 to terminate flow of liquid refrigerant to the associated evaporator. The associated unloader solenoids 28 are also deenergized so .that the associated cylinders are unloaded. 7

Inasmuch as operation of each evaporator causes loading of the number of associated cylinders required to serve the evaporator, it will be apparent that the total number of cylinders that are loaded will have sufflcient capacity to serve all of the evaporators that are rendered efiective, that is, supplied with liquid refrigerant. One advantage is that the suction pressure is maintained at a sufliciently high value for eflicient operation and to prevent frosting of the evaporators.

It will also be apparent that the motor compressor unit is operated whenever any thermostat closes its contacts to render the associated evaporators effective, and that the motor compressor unit is shut down when all of the evaporators are rendered ineffective by opening all of the thermostatic contacts. .7

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore,

that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

with each evaporator, a motor fordriving said compressor, a circuit associated with each evaporator and having means for selectively opening and closing the same, means controlled by each circuit for rendering the evaporator effective and ineiiective and for loading and unloading the associated compressor element or elements upon closing and opening of the circuit, respectively.

6. In refrigerating apparatus, the combination of a plurality of evaporators, a compressor having a compressor element or elements associated with each evaporator, a motor for driving said compressor, automatic means associated with each evaporator for initiating and terminating flow of liquid refrigerant thereto in response to a load condition thereof and for simultaneously loading and unloading, respectively, the associated compressor element or elements, and means for automatically energizing said motor in response to the action 'ofany of said automatic means in initiating flow of liquid refrigerant.

7. In a refrigerating system, the combination of a plurality of evaporator elements, a variable capacity compressor comprising a plurality of cylinders, a motor for driving said compressor, means associated .with each evaporator and Operable automatically in response to an operating condition thereof for rendering the evaporator effective and ineflective, means for varying the compressor capacity automatically in accordance with the total effective evaporator capacity by unloading fone or more cylinders while another cylinder or cylinders are loaded, and means for automatically energizing said motor whenever any evaporator is rendered effective and for deenergizing said motor when all evaporators are rendered ineffective.

8. In a refrigerating system, the combination of a plurality of evaporators, a compressor having one or more compressor elements associated with each evaporator, means associated with each evaporator for automatically and simultaneously rendering both the associated compressor element or elements and the evaporator efiective and ineffective in response to a cooling load condition of the evaporator, and means for automatically energizing said motor when any evaporator is rendered effective and deenergizing the same when all the evaporators are rendered ineffective. 7

9. In a refrigerating system, the combination of a plurality of evaporator elements, a multicylinder variable capacity compressor, a motor for driving said compressor, means associated with each evaporator for controlling the admission of liquid refrigerant thereto in response to a temperature maintained at a low value by the evaporator, and means operable automatically in response to the action of 'said controlling means for energizing and deenergizing said motor and for loading and unloading a cylinder or cylinders of the compressor to vary the compressor capacity in operation.

10. In a refrigerating system, the combination of a plurality of evaporator elements, a multicylinder variable capacity compressor, a motor for driving said compressor, means associated with each evaporator for automatically controlling the admission of liquid refrigerant thereto in response to a predetermined value of a physical condition established by the evaporator, means operable automatically to energize said motor when any control means operates to admit liquid refrigerant to the associated evaporator and for deenergizing said motor when no control means operates to admit liquid refrigerant to its associated evaporator, and means for loading and unloading a plurality of the cylinders of jmatically inaccordance with the total demand of said evaporators for fluid translation to vary the capacity of said compressor by unloading one or more cylinders while another cylinder 01' cylinders are loaded, and means for automatically energizing said motor whenever any evaporator demands fluid translation and for deenergizing said motor when no evaporator demands fluid translation.

CHAS. M. SANDERS, JR. 

